Self-lubricating device

ABSTRACT

A chemically adsorbed film having a surface layer containing fluorine groups and a stem layer chemically bonded by siloxane bonds to a substrate is formed on the surface of a frictional portion of a machine part such as a gear or a bearing or on the surface of a game ball. An excellently self-lubricating low frictional resistance machine part or game ball thus can be obtained. A frictional portion of a gear or the like, made of SiO 2  or like ceramic material, is dipped and held in a solution containing a surface active material, e.g., 
     
         CF.sub.3 (CF.sub.2).sub.7 (CH.sub.2).sub.2 SiCl.sub.3 
    
     dissolved in a non-aqueous solvent. A hydrochloric acid removal reaction is brought about between SiCl groups of the material, which contains a fluorocarbon and a chlorosilane group, and hydroxyl groups numerously present on the SiO2 surface, thus forming bonds of 
     
         CF.sub.3 (CF.sub.2).sub.7 (CH.sub.2).sub.2 Si(O--).sub.3 
    
     over the entire frictional portion surface. A fluorine-containing monomolecular film thus is formed, which is chemically bonded to the substrate and has a thickness of about 1.5 nm.

This application is a division of application Ser. No. 08/458,703, filedJun. 2, 1995, now U.S. Pat. No. 5,731,077, which is a division ofapplication Ser. No. 08/145,669, now U.S. Pat. No. 5,425,989, filed Nov.4, 1993, which is a continuation of application Ser. No. 07/840,050,filed Feb. 24, 1992, now abandoned.

FIELD OF THE INVENTION

This invention relates to machine parts offering low frictionalresistance and, more particularly, to self-lubricating micro-machines orlike machine parts. It also relates to audio and video devices offeringlow frictional resistance. It further relates to game balls and, moreparticularly, to game balls such as those used in the pachinko, smartball, pin ball, roulette and bowling games provided with a lubricatingcoated film.

BACKGROUND OF THE INVENTION

Usual frictional machine parts such as gears, bearings, rotors, shafts,crankshafts and turbines require lubrication. If the lubricant supplyceases or becomes insufficient, heat is produced at frictional portions,leading to wear or rupture of such portions. Depending on the purpose ofthe machine, however, there are cases where no lubricant can be used, orwhere great limitations are imposed on the use of lubricant. Forexample, in devices for manufacturing foods or medicines, great care ispaid lest lubricant should be occasionally introduced into the products.Great care is also paid in the case of medical devices. Further,timepieces or the like, which are used by general consumers, requirelubricants for prolonged use.

Further, micro-machines (i.e., minutia precision machines) comprisingparts of about 1 mm or less in size, can not use any lubricant becauseof the extremely small size of the parts. Making the surface as smoothas possible is the sole way of providing for a satisfactory frictionalproperty of micro-machines.

With general machine parts, however, the possibility of hazardousleakage of the lubricant exists even if great care is taken. Withtimepieces or the like, which are used by general consumers, it ispractically impossible to use a lubricant. The surface of micro-machineparts may be made smooth by a photo-lithographic process. In this case,however, limitations are imposed, and currently sufficient durabilitycan not be obtained.

At any rate, it has been impossible to obtain a high performance machinepart offering low frictional resistance.

In another aspect, in tape recorders, VTRs, DATs and otherrecording/reproducing devices, in which magnetic tapes are driven, greatcare is taken lest scars or scratches are produced on the tapes duringrunning. Scars or scratches produced on the recording medium willinterfere with necessary functions of recording and reproduction.Further, scars or scratches produced on the back surface of therecording medium will undesirably cause transferred scars or scratcheswhen a medium such as a tape is wound.

VTRs and DATs are multi-functional and high performance devices. Theyare particularly required to have long life and be highly reliable. VTRcylinder heads are rotated at high speeds of about 1,000 to 6,000 rpm.Therefore, if abnormalities occur in the rotating mechanism, the imagereproduction or reliability is greatly affected, and trouble in therotating mechanism will cause defective reproduction.

Generally, frictional parts such as bearings, rotors, shafts,crankshafts and turbines require a supply of lubricant. If the lubricantsupply ceases or becomes insufficient, the frictional sections generateheat, leading to wear and rupture.

To avoid such difficiencies, it has heretofore been the practice to makeonly the frictional surface in contact with the running tape as smoothas possible. In addition, to enhance the lubricating property of thefrictional surface of a device, it has been typical practice only tocoat the frictional surface with lubricant or to make the frictionalsurface as smooth as possible.

However, making the frictional surface as the contact surface of therunning tape as smooth as possible also reduces the friction of the tapeduring running. In addition, where lubricant is supplied to thefrictional surface of the device, the possibility of lubricant leakageexists. If oil leakage occurs in a VTR cylinder head bearing section,lubricant is spattered onto nearby parts due to high speed rotation.This can affect the VRT tape or the like adversely. Besides, there is alimitation on making smooth the frictional surface itself.

In a further aspect, game balls such as those for pachinko, smart balland bowling games can be readily contaminated. If they are contaminated,they may fail to roll smoothly, or may cause clogging of the gamemachine during the game, or they will be worn out to deteriorate theirslip. Therefore, it is necessary to make the game ball surface as smoothas possible to permit smooth rolling by washing or polishing.Heretofore, game balls are polished with cloth or the like, and in gameplaces this operation is continued until late at night. Further, it iswell known to increase the lubricity of the ball surface by making thesurface as smooth as possible or coating a lubricant on the surface.

However, limitations are imposed on permitting smooth rotation of gameballs by making the surface smooth during the molding process. Inaddition, where a lubricant is coated, the lubricant film can beseparated or worn out during use.

SUMMARY OF THE INVENTION

An object of the invention is to provide a machine part, which offerslow frictional resistance and is excellently self-lubricating.

Another object of the invention is to provide an audio or videoapparatus, which has a lubricating film capable of reducing thefrictional resistance offered to the running tape and having excellentdurability.

A further object of the invention is to provide an audio or videoapparatus, which has a lubricating film chemically bonded to thefrictional surface of the apparatus, offering low frictional resistanceand is excellently self-lubricating.

A still further object of the invention is to provide a game ball, whichhas its surface provided with a lubricating film having a uniformthickness at the nanometer level, wherein the film is excellentlydurable, wear-proof, lubricating and water- and oil-repelling.

An objective of the invention is to provide a self-lubricating devicecomprising a chemically adsorbed film as a surface layer covalentlybonded to the device by --Si--bonds, and the chemically adsorbed filmcontains fluorocarbon chain groups or hydrocarbon chain groups.

It is preferable in this invention that the chemically adsorbed film isa monomolecular film or polymer film.

It is preferable in this invention that the device is a slide member ofa machine part.

It is preferable in this invention that the device is a micro-machine.

It is preferable in this invention that the device is selected from thegroup consisting of an audio or a video apparatus.

It is preferable in this invention that the device is a travellingmagnetic tape contact member which is selected from the group consistingof a magnetic head surface and a tape guide surface.

It is preferable in this invention that the device is a rotationalmechanism including at least a frictional surface portion of a cylinderhead.

It is preferable in this invention that the device is a game ball.

It is preferable in this invention that the fluorocarbon chain orhydrocarbon chain containing the chemically adsorbed film is laminatedto a siloxane-based inner layer, the inner layer being bonded bycovalent bonds to the surface of the device, the inner layer and thechemically adsorbed film being bonded together by covalent bonds.

It is preferable in this invention that the inner layer is amonomolecular film or polymer film.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view, showing a micro-machine as in example 1 ofthe invention.

FIG. 2 is a schematic sectional view, enlarged to a molecular level,showing the surface of a micro-machine device after formation of afluorocarbon-coating monomolecular film has in example 1 of theinvention.

FIG. 3 is a schematic sectional view, enlarged to a molecular level,showing the surface of the micro-machine device as in example 2 of theinvention.

FIG. 4 is a schematic sectional view, showing the surface of themicro-machine device provided with a chemically adsorbed film (innerlayer) containing a plurality of silanol bonds as in example 2 of theinvention.

FIG. 5 is a schematic sectional view, enlarged to a molecular level,showing the surface of the micro-machine device after formation of afluorine-coating monomolecular film as in example 2 of the invention.

FIG. 6 is a schematic sectional view, showing a VTR cylinder head as inexample 3 of the invention.

FIG. 7 is a schematic sectional view, enlarged to a molecular level,showing the surface of the VTR cylinder head as in example 3 of theinvention.

FIG. 8 is a schematic sectional view, enlarged to a molecular level,showing the surface of the VTR cylinder head after formation of afluorocarbon-coating monomolecular film as in example 3 of theinvention.

FIG. 9 is a schematic sectional view, showing a VTR cylinder head as inexample 4 of the invention.

FIG. 10 is a schematic sectional view, enlarged to a molecular level,showing the surface of the VTR cylinder head as in example 4 of theinvention.

FIG. 11 is a schematic sectional view, showing the surface of the VTRcylinder head provided with a chemically adsorbed film (inner layer)containing a plurality of silanol bonds as in example 4 of theinvention.

FIG. 12 is a schematic sectional view, enlarged to a molecular level,showing the surface of the VTR cylinder head after formation of afluorine-coating monomolecular film as in example 4 of the invention.

FIG. 13 is a schematic sectional view, showing a pachinko ball as inexample 6 of the invention.

FIG. 14 is a schematic sectional view, enlarged to a molecular level,showing the surface of the pachinko ball after formation of afluorocarbon-coating monomolecular film as in example 6 of theinvention.

FIG. 15 is a schematic sectional view, showing a bowling ball as inexample 7 of the invention.

FIG. 16 is a schematic sectional view, showing the surface of thebowling ball provided with a chemically adsorbed film (inner layer)containing a plurality of silanol bonds as in example 7 of theinvention.

FIG. 17 is a schematic sectional view, enlarged to a molecular level,showing the surface of the bowling ball after formation of afluorine-coating monomolecular film as in example 7 of the invention.

DETAILED DESCRIPTION OF THE INVENTION

According to the invention, a chemically adsorbed film is formed on thesurface of at least a frictional portion of a machine part. The filmincludes a surface layer containing fluorine groups and the base layerchemically bonded by siloxane bonds to the substrate, i.e., the portionof the machine part. The machine part offers low frictional resistanceand is excellently self-lubricating. The surface layer of the chemicallyadsorbed film contains fluoroalkyl groups, and the film offers lowresistance and is excellently self-lubricating. In addition, since thestem layer of the chemically adsorbed film is chemically bonded bysiloxane bonds to the substrate, the film is excellently durable. Itdoses not readily separate from the substrate surface even when thesurface is rubbed repeatedly. Further, it has a very small thickness onthe order of nanometers to angstroms and dose not spoil the dimensionalaccuracy of the processed machine part.

Further, in a preferred embodiment of the invention, the chemicallyadsorbed film is a monomolecular film which is excellently transparentand dose not spoil the mechanical properties of the machine part.

Further, the invention is applicable to a micro-machine as a machinepart. Thus, it is possible to make the micro-machine self-lubricatingwithout using any lubricant, and to make the machine part excellentlydurable.

The machine part, to which the invention is applicable, may be made ofany material such as metals, ceramics and plastics. In addition, it maybe of any kind. The following description concerns micro-machines. Amongmicro-machine parts are gears, rotors, shafts, crankshafts, turbineswith sizes of about 1 mm and less.

Usual micro-machine parts are made of ceramics and metals, and have asurface oxide film containing hydroxyl groups. Thus, a laminatedchemically adsorbed monomolecular film based on carbon fluoride can beformed on a micro-machine part frictional portion surface by a step ofcontacting the frictional portion surface with a non-aqueous solventcontaining molecules having a straight carbon chain having achlorosilane group (SiCl_(n) X_(3-n), n representing 1, 2 or 3, Xrepresenting a functional group) at one end, e.g., a chlorosilane-basedsurface active material containing a carbon fluoride group and achlorosilane group, to precipitate a monomolecular film of the surfaceactive material on the frictional portion surface by a reaction betweenhydroxyl groups at the frictional portion surface and the material, orcontacting the frictional portion surface with a non-aqueous solventcontaining a material containing a plurality of chlorosilyl groups toprecipitate the material containing a plurality of chlorosilyl groups onthe frictional portion surface by a reaction between hydroxyl groups ofthe frictional portion surface and chlorosilyl groups of the material; astep of washing away excess material containing a plurality ofchlorosilyl groups remaining on the frictional portion surface by usinga non-aqueous organic solvent to obtain a siloxane-based monomolecularfilm of the material containing a plurality of siloxane groups on thefrictional portion surface; and a step of forming a laminated chemicallyadsorbed monomolecular film on the frictional portion surface bychemically adsorbing a silane-based surface active material containing astraight carbon chain having a chlorosilane group at one end.

In this way, a monomolecular film based on carbon fluoride having athickness at the nanometer level can be formed on the micro-machinefrictional surface portion without spoiling the functions intrinsic tothe micro-machine part. In addition, the film has excellent frictionalproperties and permits reduction of frictional resistance offered by thesurface. It is thus possible to provide a micro-machine, which issubject to less wear and highly reliable. Further, the micro-machineaccording to the invention does not require any lubricant. Furthermore,the monomolecular film formed is biocompatible, and thus themicro-machine can be inserted into a human body.

Examples of trichlorosilane-based surface active materials of thepresent invention include

CF₃ (CF₂)₇ (CF₂)₂ SiCl₃,

CF₃ CH₂ O (CH₂)₁₅ SiCl₃,

CF₃ (CH₂)₂ Si (CH₃)₂ (CH₂)₁₅ SiCl₃,

F(CF₂)₄ (CH₂)₂ Si(CH₃)₂ (CH₂)₉ SiCl₃,

F(CF₂)₈ (CH₂)₂ Si(CH₃)₂ (CH₂)₉ SiCl₃,

CF₃ COO (CH₂)₁₅ SiCl₃,

CF₃ (CF₂)₅ (CH₂)₂ SiCl₃,

CH₃ (CH₂)₉ SiCl₃,

CH₃ CH₂ O(CH₂)₁₅ SiCl₃,

CH₃ (CH₂)₂ Si(CH₃)₂ (CH₂)₁₅ SiCl₃,

CH₃ (CH₂)₆ Si(CH₃)₂ (CH₂)₉ SiCl₃,

CH₃ (CH₂)₁₀ Si(CH₃)₂ (CH₂)₉ SiCl₃,

CH₃ COO(CH₂)₁₅ SiCl₃.

Examples of lower-alkyl substituted monochlorosilane- ordichlorosilane-based surface active materials of the present inventioninclude

CF₃ (CF₂)₇ (CH₂)₂ SiCl_(n) (CH₃)_(3-n), CF₃ CH₂ O(CH₂)₁₅ SiCl_(n)(CH₃)_(3-n), CF₃ (CF₂)₇ (CH₂)₂ SiCl_(n) (C₂ H₅)_(3-n), CF₃ (CH₂)₂Si(CH₃)₂ (CH₂)₁₅ SiCl_(n) (CH₃)_(3-n), CF₃ CH₂ O(CH₂)₁₅ SiCl_(n) (C₂H₅)_(3-n), CF₃ (CF₂)₃ (CH₂)₂ Si(CH₃)₂ (CH₂)₉ SiCl_(n) (C₂ H₅)_(3-n), CF₃(CF₂)₇ (CH₂)₂ Si(CH₃)₂ (CH₂)₉ SiCl_(n) (CH₃)_(3-n), CF₃ (CF₂)₅ (CH₂)₂SiCl_(n) (CH₃)_(3-n), CF₃ COO(CH₂)₁₅ SiCl_(n) (CH₃)_(3-n)

where n represents 1or 2.

Among these examples, trichlorosilane-based surface active materials arepreferred in that chlorosilyl bonds other than those bonded to theirhydrophilic groups form intermolecular bonds with adjacent chlorosilanegroups by siloxane bonds, thereby permitting formation of a more firmlyadsorbed film.

Trichlorosilane-based surface active materials are particularlypreferred because chlorosilyl bonds other than those coupled to theirhydrophilic groups form inter-molecular bonds with adjacent chlorosilanegroups with siloxane bonds and thus permit formation of a more firmlyadsorbed film. Further,

    CF.sub.3 (CF.sub.2).sub.n (CH.sub.2).sub.2 SiCl.sub.3

where n represents an integer, most suitably 3to 25, is preferredbecause of its solubility and its water-repelling, anti-contaminatingand other functional properties. Further, with an ethylene or acetylenegroup added to or incorporated in the alkyl fluoride chain portion, thechemically adsorbed film may be crosslinked after formation byirradiating it with an electron beam of about 5 Mrads, thus furtherimproving the hardness of the chemically adsorbed film.

It is thus possible to further improve the hardness of the chemicallyadsorbed film.

The chlorosilane-based surface active material capable of use accordingto the invention is not limited to those in the form of a straight chainas noted above. It is possible to use a branched alkyl fluoride orhydrocarbon group or those having a substituted alkyl fluoride orhydrocarbon group with silicon at one end (i.e., those represented bythe formula

    R.sub.2 SiCl.sub.2, R.sub.3 SiCl , R.sup.1 R.sup.2 SiCl.sub.2

or

R¹ R² R³ SiCl where R, R¹, R² and R³ represents an fluorocarbon group orhydrocarbon group). To increase the adsorption density, however, thestraight chain form is preferred.

Further, by chemically adsorbing a material for forming an inner layermaterial having a plurality of chlorosilyl groups, e.g., SiCl₄, SiHCl₃,SiH₂ Cl₂, and Cl(SiCl₂ O)_(n) Cl₃ (where n represents an integer in arange from 1 to 20), SiCl_(m) (CH₃)_(4-m), SiCl_(m) (C₂ H₅)_(4-m) (wherem represents 1, 2or 3), and HSiCl_(p) (CH₃)_(3-p), HSiCl_(p) (C₂H₅)_(3-p) (where p represents 1 or 2), and then reacting it with water,surface chlorosilyl bonds are converted to hydrophilic silanol bonds,thus making the polymer composition hydrophilic. Among the materialscontaining a plurality of chlorosilyl groups, tetrachlorosilane (SiCl₄)is preferred in that it is highly reactive and low in molecular weight.It can, therefore, provide silanol bonds at a high density. In this way,it is possible to provide a highly hydrophilic composition compared tooxidation treatment of a polymer-containing substrate. To this surface,a chlorosilane-based surface active material containing fluoroalkylgroups may be chemically adsorbed. In this way, a chemically adsorbedfilm suitably having an increased density can be obtained.

With a machine part consisting of a plastic molding, a chemicallyadsorbed film containing fluoroalkyl groups is formed on the plasticmolding surface via siloxane bonds. The method of forming the filmsuitably comprises a step of making the plastic molding surfacehydrophilic by oxidiation treatment, and a step of chemically adsorbinga chlorosilane-based surface active material to the oxidized surface bycontacting the surface with a non-aqueous organic solvent by means ofdipping, thus forming a chemically adsorbed film containing fluoroalkylgroups via siloxane bonds.

The plastic material may be oxidized by ordinary means, e.g., oxygenplasma treatment, corona treatment, and dipping into a mixed solutioncontaining concentrated sulfuric acid and potassium dichromate (i.e., achromium-containing blend solution treatment).

The non-aqueous solvent to be used according to the invention may be anyorganic solvent, which does not dissolve the plastic material with thechemically adsorbed film to be formed thereon and is free from activehydrogen able to react with the chlorosilane-based surface activematerial. Suitable examples of the solvent are fluorine-based solvents,e.g., 1,1,dichloro-1-fluoroethane, 1,1-dichloro-2,2,2-trifluoroethane,1,1-dichloro-2,2,3,3,3-pentafluoropropane,1,3-dichloro-1,1,2,2,3-heptafluoropropane, etc., hydrocarbon-basedsolvents, e.g., hexane, octane, hexadecane, cyclohexane, etc.,ether-based solvents, e.g., dibutylether, dibenzylether, etc., andester-based solvents, e.g., methyl acetate, ethyl acetate, isopropylacetate, amyl acetate, etc.

According to the invention, a chemically adsorbed film is formed on asupport surface as a running tape surface. The chemically adsorbed filmincludes a surface layer containing fluorine groups and a stem layerchemically bonded to the surface by siloxane bonds. Thus, it is possibleto reduce the frictional resistance during running of the tape andprevent scars and scratches from being produced on the tape.

Further, since the chemically adsorbed film is formed on the surface ofa lubricating section of the audio or video device, it is possible toprovide a device, which offers low frictional resistance and isexcellently self-lubricating. That is, because of fluoroalkyl groupspresent in the surface layer of the chemically adsorbed film, thefrictional resistance, i.e., frictional resistance during tape running,can be reduced, and the frictional section of the device may be madeexcellently self-lubricating. Further, since the chemically adsorbedfilm has its stem layer chemically bonded by siloxane bonds to thesubstrate surface, it can be excellently durable and will not separatefrom the substrate surface even after repeated running or frictiongeneration at the surface. Further, since the chemically adsorbed filmaccording to the invention has a thickness on the order of nanometers toangstroms, it does not spoil the dimensional accuracy of the processedmachine.

Further, with the preferred chemically adsorbed film monomolecular film,a film having a uniform thickness can be obtained which is excellentlytransparent and does not spoil mechanical characteristics.

Since a monomolecular film based on carbon fluoride and having athickness at the nanometer level can be formed on the surface of a VTRcylinder head, the intrinsic functions of the head are not spoiled. Inaddition, the film has excellent frictional properties and frictionalresistance of the surface is reduced. It is thus possible to provide aVTR cylinder head which has less frictional resistance, is highlyreliable and does not need any lubricant.

According to the invention, a chemically adsorbed film is formed on agame ball surface such that it is chemically bonded to the surface bysiloxane bonds. The film offers low frictional resistance, when the ballis rolling, is excellently lubricating and can prevent generation ofscars and scratches. Since its surface layer contains fluoroalkylgroups, it offers low frictional resistance, i.e., low frictionalresistance at the time of rolling, and is excellently water- andoil-repelling and anti-contaminating. Further, since chemical bonds areformed via siloxane bonds, it is excellently durable. Thus, it does notreadily separate from the substrate surface even if the surface isrepeatedly rolled or moved frictionally. Further, since its thickness ison the order of nanometers to angstroms, it does not spoil thedimensional accuracy of the processed game ball. Further, with thepreferred chemically adsorbed monomolecular film, a uniformity thin andexcellently transparent film can be obtained.

Preferred substrates according to the invention include game balls suchas those used for pachinko, smart ball, pin ball, roulette, bowling andlike games. Usually, a metal substrate contains hydroxyl groups at thesurface. However, in case of a resin or like substrate or where a metalsurface does not contain so many exposed hydroxyl groups, the surfacemay be treated by a plasma treatment or irradiation with ultravioletrays or provided with a siloxane layer, thus providing many hydroxygroups exposed at the surface. Then, a laminated chemically adsorbedmonomolecular film based on carbon fluoride, may be formed on thesubstrate surface by a step of contacting the substrate surface with anon-aqueous solvent containing molecules containing a straight carbonchain having a chlorosilane group (SiCl_(n) X_(3-n), n representing 1, 2or 3, X representing a functional group) at one end, e.g., achlorosilane-based surface active material containing a fluorocarbon anda chlorosilane group for a reaction between hydroxyl groups at thesubstrate surface and chlorosilyl groups of the surface active materialto precipite a monomolecular film on the substrate surface, orcontacting the substrate with a non-aqueous solvent containing a surfaceactive material containing a plurality of chlorosilyl groups for areaction between hydroxyl groups at the substrate surface andchlorosilyl groups of the surface active material to cause precipitateof a monomolecular film on the substrate surface; a step of washing awayexcess material containing a plurality of chlorosilyl groups from thesubstrate surface to obtain a siloxane-based monomolecular filmcontaining a plurality of chlorosilyl groups on the substrate; and astep of chemically adsorbing a silane-based surface active materialcontaining a straight carbon chain having a chlorosilane group at oneend to the substrate to form a laminated chemically adsorbedmonomolecular film.

Thus, a fluorocarbon-based monomolecular film having a thickness at thenanometer level can be formed on the game ball surface without causingany change in the dimension or shape of the game ball. This film has anexcellent frictional property and permits reduction of the frictionalresistance of the surface. It is thus possible to obtain a film, whichoffers less frictional resistance and is highly reliable and excellentlywater- and oil-repelling and anti-contaminating.

EXAMPLE 1

A processed micro-machine 1 (with a gear 1a and a shaft 1b) made of SiO₂and having a diameter of 100 microns was prepared (FIG. 1) and washedwith an organic solvent. Then, a solvent containing a materialcontaining a fluorocarbon and a chlorosilane group was prepared bydissolving about 2% of

    CF.sub.3 (CF.sub.2).sub.7 (CH.sub.2).sub.2 SiCl.sub.3

in, for example, a mixed solvent composed of 80% of n-hexadecane (ortoluene or xylene or dicyclohexyl), 12% of carbon tetrachloride and 8%of chloroform. At least a frictional portion 1 of the micro-machine (orthe whole micro-machine) was dipped and held in the solution for about 2hours. Thus, a dehydrochlorination reaction was brought about betweenhydroxyl groups numerously present at the surface and the SiO₂ and--SiCl groups of the material containing a fluorocarbon and achlorosilane group, thus producing bonds of represented by by formula 1##STR1## at the film surface. The film was then washed with chloroformto remove unreacted material remaining on the surface, followed bywashing with water or exposing to air containing moisture. The --SiClgroup was changed to a --SiOH group as the formula 2!. ##STR2##

Each silanol group (--SiOH) was then dehydrochlorinated and crosslinkedto form a siloxane bond (--SiO--) after drying as in the formula 3!.Drying temperature may be room temperature or above. ##STR3##

A fluorine-containing monomolecular film 2 could be formed over theentire surface of the frictional section. It was chemically bonded tothe gear and shaft and had a thickness of about 15 angstroms (1.5 nm).The threshold surface energy of the film was measured (measuringinstrument: "Automatic Contact Angle Gauge Model CA-Z" by Kyowa KaimenKagaku Co., Ltd.) and found to be 15 dynes/cm. The dynamic frictioncoefficient was found to be 0.15 (measuring instrument: "Fully AutomaticDynamic Friction Coefficient Gauge Model DFPM-SS" by Kyowa Kaimen KagakuCo., Ltd.)

This monomolecular film was sufficiently thin compared to the dimensionsof the gear and shaft. In addition, since it contained fluorocarbongroups, it was highly lubricating. Further, since it was firmlychemically bonded, it could withstand high speed rotation and did notseparate. Further, the gear was tested by rotating it by 10,000rotations, and it could withstand about 30 times the number of rotationsin the case of a non-treated gear.

The above washing step with the chloroform was omitted, and afluorocarbon polymer film was adsorbed to the substrate. Thefluorocarbon-based polymer film was in satisfactorily close contact withthe substrate. The film exhibited low frictional resistance and wasexcellently self-lubricating.

EXAMPLE 2

A part made of alumina (or such metal as stainless steel), whichcontains less hydroxyl groups although it is hydrophilic, was treated.The alumina part 11 was dipped and held for about 30 minutes in asolution prepared by dissolving 1% by weight of a material containing aplurality of chlorosilyl groups, e.g., SiCl₄ being small in molecularsize and greatly reactive with respect to hydroxyl groups, thus having agreat effect of rendering the surface uniformly hydrophilic in anon-aqueous solvent, e.g., chloroform solvent. As a result, adehydrochlorination reaction was brought about due to hydrophilic --OHgroups 12 more or less present at the surface of the alumina part 1(FIG. 3), whereby a chlorosilane monomolecular film of the materialcontaining a plurality of trichlorosilyl groups was formed.

As an example, using SiCl₄ as the material containing a plurality ofchlorosilyl groups, a hydrochloric acid removal reaction was broughtabout on the surface due to a small quantity of hydrophilic --OH groupsbeing exposed at the part surface 11. Molecules as represented byformulas 4 and/or 5 were formed. ##STR4##

These bonds were connected to the surface by --SiO-- bonds.

Subsequently, the part was washed with a non-aqueous solvent, e.g.,chloroform to remove unreacted SiCl₄ molecules, and then with water thusobtaining a siloxane monomolecular film 13 (FIG. 4) on the part surfaceas shown by formulas 6 and/or 7. ##STR5##

The above washing step with the chloroform was omitted, and asiloxane-based polymer film was adsorbed to the substrate. Thesiloxane-based polymer film was in satisfactorily close contact with thesubstrate.

The monomolecular film 13 was completely bonded by chemical bonds of--SiO-- to the part surface and did not separate. In addition, itssurface contained numerous silanol (--SiOH) bonds corresponding to aboutthree times the initial number of hydroxyl groups.

As a further example, a part provided with a monomolecular film formedon its surface and containing numerous SiOH bonds, was dipped and heldfor about one hour in a non-aqueous solution containing a materialcontaining a fluorocarbon and a chlorosilane group, e.g., a solutionprepared by dissolving about 3 wt. % of

    CF.sub.3 (CF.sub.2).sub.7 (CH.sub.2).sub.2 SiCl.sub.3

in a solvent containing 80 wt. % of n-hexadecane, 12 wt. % of carbontetrachloride and 8 wt. % of chloroform. The film was then washed withchloroform to remove unreacted material remaining on the surface,followed by washing with water or exposing to air containing moisture.As a result, bonds of

    CF.sub.3 (CF.sub.2).sub.7 (CH.sub.2).sub.2 Si (O--).sub.3

were formed on the surface, and a fluorine-containing monomolecular film14 was formed as above in formulas 1 to 3. The film was densely formedover the entire part surface and chemically bonded to the inner siloxanemonomolecular film. Its thickness was about 1.5 nm (FIG. 5). Thislaminated monomolecular film did not separate in a peel-off test. Itoffered about one half the frictional resistance compared to directlyforming the fluorine-containing monomolecular film on the part surface.

While the above embodiment used

    CF.sub.3 (CF.sub.2).sub.7 (CH.sub.2).sub.2 SiCl.sub.3

as the fluorine-containing surface active material, if an ethylene oracethylene group is added to or incorporated in the alkyl chain part,crosslinking can be obtained by irradiation with an electron beam at 5Mrad. after the monomolecular film formation. The hardness of the filmthus can be further improved. As shown in the above example, alubricating fluorocarbon-based monomolecular film having a nanometerlevel thickness, which is sufficiently small compared to themicro-machine part dimensions, is formed on the micro-machine partfrictional portion surface, and the intrinsic functions of themicro-machine are not spoiled. Further, the fluorocarbon-basedmonomolecular film is biocompatible, can offer very low frictionalresistance, and does not separate or wear out. Thus, it is veryeffective for a micro-machine which is used inside the human body, andin which no lubricant can be used.

According to the invention of a chemically adsorbed film, which includesa surface layer containing fluorine and a stem layer chemically bondedby siloxane bonds to the substrate, is formed on at least a frictionalportion surface of a machine part. Thus, it is possible to provide amachine part which offers low frictional resistance and is excellentlyself-lubricating.

Further, with the preferred chemically adsorbed monomolecular film, athin film having a uniform thickness can be obtained which isexcellently transparent and does not spoil the dimensional accuracy ofthe processed machine.

Further, with the preferred micro-machine as a machine part,self-lubricating properties and excellent durability can be provided sothat no lubricant need.

EXAMPLE 3

A shaft 21, a rotational cylinder 22 and a bearing 33 of a processed VTRcylinder head (FIG. 6) were washed with an organic solution. Anon-aqueous solution containing a material containing a fluorocarbon anda chlorosilane group, was prepared by dissolving, for example, about 2wt. % of

    CF.sub.3 (CF.sub.2).sub.7 (CH.sub.2).sub.2 SiCl.sub.3

in a blend solvent composed of 80% a by weight of n-hexadecane (ortoluene or xylene or dichlorohexyl), 12% by weight of carbontetrachloride and 8% by weight of chloroform. The shaft 21, rotationalcylinder 22 and bearing 23 were dipped and held for about 2 hours in thesolution. As a result, a dehydrochlorination reaction was brought aboutbetween hydroxyl groups numerously contained at the surface of a naturaloxide film 24 on the surface of the shaft 21, rotational cylinder 22 andbearing 23 and the --SiCl groups in the material containing afluorocarbon and a chlorosilane group. The film was then washed withchloroform to remove unreacted material remaining on the surface,followed by washing with water or exposing to air containing moisture.As a result, bonds of

    CF.sub.3 (CF.sub.2).sub.7 (CH.sub.2).sub.2 Si (O--).sub.3

were formed on the surface, and a fluorine-containing monomolecular film26 was formed same as above formulas 1 to 3. The film was chemicallybonded to the surface of the shaft 21, rotational cylinder 22 andbearing 23 and had a thickness of about 1.5 nm (FIG. 8).

The threshold surface energy of the film was measured (measuringinstrument: "Automatic Contact Angle Gauge Model CA-Z" by Kyowa KaimenKagaku Co., Ltd.) and found to be 15 dynes/cm. The dynamic frictioncoefficient was found to be 0.15 (measuring instrument: "AutomaticDynamic Friction Gauge Model DFPM-SS" by Kyowa Kaimen Kagaku Co., Ltd.).

This monomolecular film was sufficiently thin compared to the dimensionsof the shaft, rotational cylinder and bearing. In addition, it containedfluorocarbon groups and was highly lubricating. Further, it was veryfirmly chemically bonded, and thus withstood high speed rotation and didnot separate. Further, the shaft 21, rotational cylinder 22 and bearing23 were assembled into a VRT cylinder head which was then tested byrotating it at 2,500 rpm. The head could withstand use for about doublethe period compared to a non-treated head.

EXAMPLE 4

This example concerns a VTR cylinder head made of a material, whichcontains less hydroxyl groups although it is hydrophilic. The VRTcylinder head, like Example 3, comprised a shaft 31, a rotationalcylinder 32 and a bearing 33 (FIG. 9). These parts were dipped and heldfor about 30 minutes in a solution prepared by dissolving 1% a by weightof a material containing a plurality of chlorosilyl groups, e.g.,Cl(SiCl₂ O)₂ SiCl₃ being small in molecular size and highly reactivewith respect to the hydroxyl groups, thus having a great effect ofmaking the surface of the shaft 31, rotational cylinder 32 and bearing33 uniformly hydrophilic, in a non-aqueous solvent, e.g., chloroformsolvent. As a result, a dehydrochlorination reaction was brought abouton the surface of the shaft, rotational cylinder and bearing due tohydrophilic --OH groups 35 being more or less present at the surface,thus forming a chlorosilane monomolecular film of the materialcontaining a plurality of chlorosilyl groups.

As an example, a dehydrochlorination reaction was brought about on theVTR cylinder shaft surface 34 due to a small quantity of hydrophilic--OH groups 35 being exposed at the surface. Bonds as represented byformulas 8 and/or 9 were thus secured to the surface by --SiO-- bonds.##STR6##

Subsequently, the shaft was washed with a non-aqueous solvent, e.g.,chloroform, and then with water, thus obtaining on the part surface asiloxane monomolecular film 36 (FIG. 11) as represented by formulas 10and/or 11. ##STR7##

The monomolecular film 36 thus formed was perfectly bonded to the VTRcylinder shaft via chemical bonds of --SiO-- and did not separate. Thismonomolecular film had numerous --SiOH bonds present at the surface andcorresponded to about 6 to 7 times the initial number of hydroxylgroups.

Further, the VTR cylinder shaft provided with the monomolecular filmhaving numerous --SiO bonds at the surface, was dipped and held forabout one hour in a non-aqueous solution containing a materialcontaining a fluorocarbon and a chlorosilane group, e.g., a solutionprepared by dissolving about 2% by weight of CF₃ (CF₂)₇ (CH₂)₂ SiCl₃, ina solvent containing 80% by weight of n-hexadecane, 12% by weight ofcarbon tetrachloride and 8% by weight of chloroform. The film was thenwashed with chloroform to remove unreacted material remaining on thesurface, followed by washing with water or exposing to air containingmoisture. As a result, bonds of

    CF.sub.3 (CF.sub.2).sub.7 (CH.sub.2).sub.2 Si(O--).sub.3

were formed on the surface, and a fluorine-containing monomolecular film37 was formed as above in formulas 1 to 3. The film was chemicallybonded to the inner siloxane monomolecular film 36 and had a thicknessof about 1.5 nm (FIG. 12). The monomolecular film did not separate in apeel-off test.

The frictional resistance of the film was about one fold compared to afluorine-containing monomolecular film being formed directly on the partsurface.

As shown in the above example, the VTR cylinder shaft was contacted witha non-aqueous solution containing a chlorosilane-based surface activematerial containing a fluorocarbon and a chlorosilane group to cause areaction between hydroxyl groups at the shaft surface and chlorosilylgroups so as to precipitate a monomolecular film on the substratesurface. The fluorocarbon-based monomolecular film thus formed has athickness at the nanometer level and is chemically bonded to the headsurface. Thus, it does not spoil the intrinsic functions of the VTRcylinder shaft, and it is possible to obtain a VTR cylinder shaft whichhas excellent frictional properties, offers low frictional resistanceand is excellently self-lubricating and durable.

EXAMPLE 5

A chemically adsorbed monomolecular film as in Example 3 and as shown inFIG. 6, was formed on the outer periphery of a rotational cylinder andthe surface of a tape guide. The chemically adsorbed monomolecular filmhad a very low frictional resistance at the time of tape running and wasexcellently durable. In addition, frictional scars or scratches did noteasily form on the tape, and the film was excellently self-lubricating.

As shown above, the self-lubricating film according to the invention isextensively applicable to audio and video apparatus such as the surfaceof tape recorder magnetic heads (including a de-magnetization head), thesurface of a VTR rotational cylinder (including a head), a DATrotational cylinder surface and bearing section, the surface of astationary head of VTR or DAT, a tape guide, etc.

As has been shown, according to the invention a chemically adsorbedfilm, which includes a surface layer containing fluorine groups and astem layer chemically bonded by siloxane bonds to the substrate, isformed on the substrate surface as a running tape surface, and thus itis possible to reduce the frictional resistance at the time of taperunning and thus prevent frictional scars and scratches from beingproduced on the tape.

Further, with the chemically adsorbed film formed on the lubricatingportion surface of an audio or video device, it is possible to provide adevice which offers low frictional resistance and is excellentlyself-lubricating. More specifically, since the surface layer of thechemically adsorbed film contains fluoroalkyl groups, it is possible toreduce the frictional resistance, i.e., the frictional resistance at thetime of tape running, and an excellently self-lubricating frictionalportion of the device can be obtained. Further, since the stem portionof the chemically adsorbed film is chemically bonded by siloxane bondsto the substrate, an excellently durable film can be obtained which doesnot readily separate from the substrate surface when the surface isrepeatedly run or rubbed. Further, since the chemically adsorbed filmaccording to the invention is very thin, having a thickness on the orderof nanometers to angstroms, it will not spoil the dimensional accuracyof the processed machine.

Further, since the chemically adsorbed film according to the inventionmay be a monomolecular film and may have a thickness at the nanometerlevel, it is excellently transparent and will not spoil the dimensionalaccuracy of the processed machine. In addition, it can provide theself-lubricating property without need of any lubricant as well as beingexcellently durable. Thus, it greatly reduces maintenance.

EXAMPLE 6

A pachinko ball was washed with an organic solution and then dipped andheld for about 2 hours in a solution containing a material having afluorocarbon and a chlorosilane group, e.g., a solution prepared bydissolving about 2 wt. % of CF₃ (CF₂)₇ (CH₂)₂ SiCl₃, in a solventcontaining 80% by weight of n-hexadecane (or toluene or xylene ordicyclohexyl), 12% by weight of carbon tetrachloride and 8% by weight ofchloroform. As a result a dehydrochlorination reaction was brought aboutbetween hydroxyl groups 43 numerously present at the surface of anatural oxide film 42 formed on the surface of the pachinko ball 41(FIG. 13) and between --SiCl groups of the material containing afluorocarbon and a chlorosilane group. The film was then washed withchloroform to remove unreacted material remaining on the surface,followed by washing with water or exposing to air containing moisture.As a result, bonds of

    CF.sub.3 (CF.sub.2).sub.7 (CH.sub.2).sub.2 Si (O--).sub.3

were formed on the surface, and a fluorine-containing monomolecular film44 was formed as above in formulas 1 to 3 (FIG. 14). The film waschemically bonded to the surface of the pachinko ball 41 and had athickness of about 1.5 nm.

It was very firmly chemically bonded and did not separated.

The above washing step with the chloroform was omitted, and afluorocarbon polymer film was adsorbed to the substrate. Thefluorocarbon-based polymer film was in satisfactorily close contact withthe substrate. The film had low frictional resistance and wasexcellently self-lubricating.

EXAMPLE 7

A bowling ball 41 was dipped and held for about 30 minutes in a solutionprepared by dissolving 1% by weight of a material containing a pluralityof chlorosilyl groups, e.g., SiCl₄ being small in molecular size andhighly active with respect to the hydroxyl groups, thus providing agreat effect of making the surface of the bowling ball 41 uniformlyhydrophilic, in a non-aqueous solvent, e.g., chloroform solvent. As aresult, a hydrochloric acid removal reaction was brought about on thesurface 42 of the bowling ball 41 due to hydrophilic --OH groups 43 moreor less present at the surface 42 (FIG. 15), thus forming a chlorosilanemonomolecular film of the material containing a plurality of chlorosilylgroups.

By using SiCl₄ as the material containing a plurality of chlorosilylgroups, a dehydrochlorination reaction was brought about on the bowlingball surface 42 due to a small amount of --OH groups exposed at thesurface 42. Molecules represented above the formulas 1 and/or 2 werethus secured by --SiO-- bonds to the surface.

Subsequently, the bowling ball was washed with a nonaqueous solvent,e.g., chloroform, and then with water, thus removing unreacted SiCl₄particles. A siloxane monomolecular film 44 as represented above informulas 6 and/or 7 was obtained on the bowling ball surface 42 (FIG.16).

The above washing step with the chloroform was omitted, and asiloxane-based polymer film was adsorbed to the substrate. Thesiloxane-based polymer film was in satisfactorily close contact with thesubstrate.

The monomolecular film 45 thus obtained was perfectly bonded by chemicalbonds of --SiO-- to the bowling ball surface 42 and did not separate. Ithad numerous --SiOH bonds at the surface, the bonds corresponding to theinitial number of hydroxyl groups.

The bowling ball provided with the monomolecular film formed thereon andcontaining numerous --SiOH bonds at the surface, was dipped and held forabout one hour in a nonaqueous solution containing a material containinga fluorocarbon and a chlorosilane group, e.g., a solution prepared bydissolving about 2% by weight of

    CF.sub.3 (CF.sub.2).sub.7 (CH.sub.2).sub.2 SiCl.sub.3

in a solvent containing 80% by weight of hexadecane, 12% by weight ofcarbon tetrachloride and 8% by weight of chloroform. The film was thenwashed with chloroform to remove unreacted material remaining on thesurface, followed by washing with water or exposing to air containingmoisture. As a result, bonds of

    CF.sub.3 (CF.sub.2).sub.7 (CH.sub.2).sub.2 Si(O--).sub.3

were formed on the surface, and a fluorine-containing monomolecular film46 was formed as above in formulas 1 to 3. It was chemically bonded tothe inner siloxane monomolecular film 45 and had a thickness of about1.5 nm (FIG. 17). It did not separate in a peel-off test.

The above washing step with the chloroform was omitted, and afluorocarbon polymer film was adsorbed to the substrate. Thefluorocarbon-based polymer film was in satisfactorily close contact withthe substrate. The film had low frictional resistance and wasexcellently self-lubricating.

As has been shown, the coating film according to the invention isexcellently lubricating and water- and oil-repelling, durable andwear-resistant, and it is suitably applicable to game balls used in gamemachines such as those for pachinko, bowling, smart ball, billiard androulette games.

Since the chemically adsorbed film according to the invention ischemically bonded by siloxane bonds to the game ball surface, thefrictional resistance is low when the ball is rolling. In addition, thefilm is excellently lubricating and prevents generation of scars andscratches. Further, since the surface layer of the chemically adsorbedfilm contains fluoroalkyl groups, it has low frictional resistance,i.e., the frictional resistance when the ball is rolling is low. Thefilm is also excellently water- and oil-repelling andanti-contaminating. Further, since it is chemically bonded via siloxanebonds, it is excellently durable and did not readily separate from thesubstrate surface even if it is repeatedly used for rolling orfrictional movement. Further, with the preferred the chemically adsorbedmonomolecular film, the film is excellently transparent and does notspoil the dimensional accuracy of the processed game ball. A uniformthickness can also be obtained.

As has been shown, the invention is greatly beneficial to industry.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is to be considered in all respects as illustrative and notrestrictive, the scope of the invention being indicated by the appendedclaims rather than by the foregoing description and all changes whichcome within the meaning and range of equivalency of the claims areintended to be embraced therein.

We claim:
 1. A self-lubricating slide member of a machine part of adevice comprising a chemically adsorbed film as a surface layer of saiddevice covalently bonded to said device by --Si-- bonds, said chemicallyadsorbed film comprising fluorocarbon chain groups or hydrocarbon chaingroups, wherein said device is selected from the group consisting of anaudio apparatus and a video apparatus.
 2. The self-lubricating deviceaccording to claim 1, wherein said chemically adsorbed film is amonomolecular film or polymer film.
 3. The self-lubricating deviceaccording to claim 1, wherein the fluorocarbon chain groups compriseseveral carbon groups and the end of the fluorocarbon chain comprisesCF₃ (CF₂)_(n), wherein n is at least 2.